As the purified naïve B cell populations still contain contaminating unconventional memory B cells (IgD-/CD27-) (S2A Fig), which do not require EBNA-LP for outgrowth and cellular transformation [32,40], tdTomato negative LCLs were observed following LPKO infection in both untransfected and cells trans-complemented with only tdTomato in some donors (Figs 1E and S2E). Here, CD27 is linked to infection.